/* mpz_root(root, u, nth) --  Set ROOT to floor(U^(1/nth)).

   Return an indication if the result is exact.

Copyright 1999-2003, 2005, 2012 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify

it under the terms of either:

  * the GNU Lesser General Public License as published by the Free

    Software Foundation; either version 3 of the License, or (at your

    option) any later version.

or

  * the GNU General Public License as published by the Free Software

    Foundation; either version 2 of the License, or (at your option) any

    later version.

or both in parallel, as here.

The GNU MP Library is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

You should have received copies of the GNU General Public License and the

GNU Lesser General Public License along with the GNU MP Library.  If not,

see https://www.gnu.org/licenses/.  */

#include <stdio.h>    /* for NULL */

#include "gmp-impl.h"

int

mpz_root (mpz_ptr root, mpz_srcptr u, unsigned long int nth)

{

  mp_ptr rootp, up;

  mp_size_t us, un, rootn, remn;

  TMP_DECL;

  us = SIZ(u);

  /* even roots of negatives provoke an exception */

  if (UNLIKELY (us < 0 && (nth & 1) == 0))

    SQRT_OF_NEGATIVE;

  /* root extraction interpreted as c^(1/nth) means a zeroth root should

     provoke a divide by zero, do this even if c==0 */

  if (UNLIKELY (nth == 0))

    DIVIDE_BY_ZERO;

  if (us == 0)

    {

      if (root != NULL)

  SIZ(root) = 0;

      return 1;     /* exact result */

    }

  un = ABS (us);

  rootn = (un - 1) / nth + 1;

  TMP_MARK;

  /* FIXME: Perhaps disallow root == NULL */

  if (root != NULL && u != root)

    rootp = MPZ_NEWALLOC (root, rootn);

  else

    rootp = TMP_ALLOC_LIMBS (rootn);

  up = PTR(u);

  if (nth == 1)

    {

      MPN_COPY (rootp, up, un);

      remn = 0;

    }

  else

    {

      remn = mpn_rootrem (rootp, NULL, up, un, (mp_limb_t) nth);

    }

  if (root != NULL)

    {

      SIZ(root) = us >= 0 ? rootn : -rootn;

      if (u == root)

  MPN_COPY (up, rootp, rootn);

    }

  TMP_FREE;

  return remn == 0;

}